Decomposition of palladium acetate and C60 fullerite during thermal evaporation in PVD process

The mechanisms of thermal decomposition of evaporated material during Physical Vapor Deposition (PVD) process depend on the kind of evaporated material. Such parameters of PVD process as deposition rate, source temperature and deposition time should be carefully selected taking into account the properties of material. Deposited films can span the range of chemical compositions based on the source materials. The nanostructural carbon films in form of palladium nanograins embedded in various carbonaceous matrixes were obtained by thermal evaporation during PVD process from two separated sources containing C60 fullerite and palladium acetate, both in a form of powder. The evaporation was realized by resistive heating of sources under a dynamic vacuum of 10-3 Pa. The influence of decomposition path of evaporated materials on the film structure has been discussed. Prepared C-Pd films were characterized using thermo-gravimetric method, differential thermal analysis, infrared spectroscopy and X-ray diffraction. The influence of decomposition of Pd acetate and fullerite on the final film structure was also shown.

THE PROTON SPIN DECOMPOSITION: PATH DEPENDENCE AND GAUGE SYMMETRY

We discuss the different types of decomposition of the proton spin. We stress that, despite their lack of uniqueness, the Chen et al. and Wakamatsu decompositions are perfectly measurable. We argue that a large part of the recent controversies boils down to the fact that there actually exist two types of gauge transformations in the Chen et al. approach, where physical and gauge degrees of freedom of the gauge potential are explicitly separated. By carefully distinguishing these two types of gauge transformations, one can easily understand how the concepts of gauge invariance, Stueckelberg symmetry, path dependence and measurability are linked to each other.

In-situ Remediation of Hydrogen Fluoride during a Detonation Event

ABSTRACTHydrogen fluoride (HF) is a known product from the combustion or detonation of explosives formulated with fluoropolymer binder systems. This presents the user with elevated risk levels, particularly during unintended combustion events or detonations in close combat situations. In an effort to remediate the production of HF, calcium disilicide was added to explosive formulations in an effort to decrease the amount of HF formed. First, VitonA/calcium disilicide mixtures were made and the thermal decomposition characteristics studied using thermal gravimetric/differential thermal analysis. The activation energy ranged from approximately 145-190 kJ/mol, indicative of C-F scission in the Viton binder prior to calcium fluoride formation. An energetic formulation was made which consisted of approximately a 5/3 mass ratio of Viton/CaSi2. Combustion calorimetry in oxygen and air and subsequent analysis of the residues using x-ray diffraction (XRD) and energy dispersive x-ray analysis (EDS) revealed that calcium fluoride formed. The amount of HF reduced was determined by trapping off gases in a cooling loop, rinsing into water, and analysis in anion exchange chromatography. Upon introduction of calcium disilicide into the formulation, a ~30% decrease in HF formation was observed along with appearance of CaF2 and free Si in the residue. Such products are consistent with the mechanism following a general decomposition path of 2F + CaSi2→CaF2+2Si. The same formulation was detonated, and upon product analysis it was determined the decomposition path followed nearly the same route with a net decrease in HF formation, but with a portion of the silicon oxidizing slightly further to SiO2.